In general, in a drum washer, washing is performed by using friction between a drum and laundries, the drum rotated by receiving a driving force of a motor, when detergent, wash water, and laundries are thrown in the drum, such that laundries are less damaged or tangled, and beating and rubbing washing is effected.
A combination dryer and drum washer for performing not only washing and dehydrating but also drying process is on an increasing trend following the trend of improvement and high quality of the drum washer.
The combination dryer and drum washer dries laundry by sucking up outside air into a fan and a heater provided at an outside of a tub, heating the air, and blowing the heated high temperature air into the tub.
A drum type dryer that is not a combination dryer and drum washer is for drying a large amount of laundries at a time in a short period of time by performing just drying.
The dryer is an apparatus for automatically drying a drying object after washing is ended. The dryer dries the drying object to be dried, such as a clothing, thrown in a drying drum by introducing an outside air, heating the external device by using a heater, and blowing the heated high temperature air into the drying drum in a rotating state.
Hereinafter, an automatic drying apparatus applied to a conventional drum washer for automatic drying and to a drum type dryer, is described as follows.
FIG. 1 illustrates a structure showing an example of a location of a temperature sensor used for determining dryness in an automatic dry washer.
Generally, related art performs drying by selecting a drying course a user wants and setting an appropriate drying time according to a load of laundry.
However, the manual drying method does not satisfy dryness the user desires because drying is not performed exactly and the laundry is less dried, or in contrast, over dried.
For solving the problem, as illustrated in FIG. 1, developed is a method for performing drying by detecting temperatures changed in process of drying by means of a tub temperature sensor (Ttub) provided in a tub 11 for detecting temperature in the tub and a duct temperature sensor (TA1) provided in a duct 12 for detecting temperature of the duct, and automatically determining dryness according to difference value (ΔT) of the detected tub temperature and the duct temperature (TA1).
As aforementioned, the method for performing drying includes a step of checking humidity in a washing tub indirectly by using the temperature difference of the temperature in the tub and the temperature in the duct. In other words, expected humidity is calculated by taking a temperature detection value from a temperature sensor of the duct or tub.
FIGS. 2a and 2c illustrate a structure of an electrode sensor including a drying drum, and a circuit structure thereof.
The automatic drying apparatus determining dryness by using the electrode sensor, as illustrated in FIGS. 2a and 2b, includes two electrode separated provided at a particular location in the drum a drying object to be dried is thrown therein, and a resistance value changes according to an amount of moisture contained when the electrodes and the drying object to be dried comes in contact.
Therefore, a voltage value is changed according to the changing resistance value, and micom reads the voltage value for determining dryness.
In other words, the resistance value is increased when the amount of moisture contained in the drying object to be dried is decreased. The voltage value is increased in proportion to the resistance value, and the micom determines a point of ending the drying process when the value is reached to a predetermined value.
However, in the method of indirectly determining dryness by using the temperature sensor or the electrode sensor, it is difficult to determine exact dryness because the amount of moisture contained is not directly detected, but the resistance value changed according to temperature of air for drying, or the amount of moisture contained in the drying object to be dried is detected, and the humidity is indirectly calculated.
When the dryness is determined by using the temperature sensor, a passage structure is changed and it is difficult to perform drying exactly due to a location of the temperature sensor in the tub, deviation in the temperature sensor itself, deviation of the duct structure, and deviation of the heater performance.
Particularly, there is a problem for performing drying exactly because the dryness is not determined consistently for all weights.
When the dryness is determined by using the electrode sensor, because of a characteristic of detection by contact with the drying object to be dried, it is difficult to detect dryness for a small amount of laundry, over drying or less drying may be generated, thereby generating waste of power consumption.